In recent years, mobile communications have become ubiquitous, in many countries, for voice and various data services via mobile handset or smartphone type devices as well as for wireless communications for portable data devices like netbook and laptop personal computers. There are situations where it is desirable to determine the position of a mobile device, and various industry players have developed technologies to meet such demands. For example, in the US today, most mobile devices are equipped with Global Positioning System (GPS) receivers/processors sufficient to enable emergency services to obtain information as to the position of a device as part of the processing of an emergency call, e.g., to 911. The advanced positioning capabilities of such mobile devices, however, have also enabled service providers to offer location based services and applications today, some of which allow a user of a mobile device to learn their present position and possibly obtain information about that locale and/or related navigation information, via the mobile device itself.
Wireless carriers use various location determination methods today. Many of the current techniques require prior knowledge of locations of wireless network equipment that may be sending and/or receiving transmissions over the air to/from a mobile station seeking a position determination. A knowledge base or database of cell site and/or sector information is sometimes referred to as a base station almanac or “BSA.” Some location determination methods (e.g., Advanced Forward Link Trilateration (AFLT)) require accurate and complete BSA information. The network may also offer assistance to the mobile station in a GPS type position determination based in part on an initial position determination from identification of one or more base stations detectable by the mobile station and position information about the detectable base station(s) from the BSA.
Determination of the position of a mobile device has many useful applications. For example, a “where am I” type location based service is useful in navigation. Another example is a “where is my child” service whereby a parent can determine the position of the mobile device of her or his child. Wireless/mobile communication networks offer a number of standard technologies to support position determinations for these location based services as well as position determinations for emergency services like 911. In many cases, the position determination is based on global positioning satellite GPS signal processing, either by the mobile device alone or with some assistance via the network. However, GPS may not be available in certain areas, such as urban canyons, inside large buildings, and the like, where a device may be unable to detect signals from a sufficient number of GPS satellites. Another method of position determination, AFLT, involves triangulation using base station identification and strength of signals that the device receives from cell towers. However, the AFLT method tends to be costly.
In addition to the services available from wireless/mobile communication networks, many localities also offer wireless Internet access via wireless local area network (WLAN) technologies. A WLAN uses over the air transmission of radio signals to communicate with at least some devices. A WLAN provides flexible network connectivity, making it possible for mobile data users to stay connected as they move freely within a building, around a campus, or in public hot spots (e.g. airports, hotels, and other public spaces). Wi-Fi (or sometimes WiFi) is a trademark of the Wi-Fi Alliance, which is used describe wireless connectivity technologies for a WLAN based on the IEEE 802.11 standards. Although originally developed for data applications, like web browsing, document sharing and email, the broadband packet communication connectivity of Wi-Fi and other types of WLAN can also be used for real-time streaming media communications like voice calls video conferencing. Increasingly, mobile devices can operate via Wi-Fi as an alternative to the wireless/mobile communication network, for example, when Wi-Fi may be cheaper or when a user is at an area that receives poor or no service from a wireless/mobile communication network.
Incorporation of Wi-Fi communications presents additional issues with regard to consistent accurate position determination. When operating via a Wi-Fi access point, it may still be possible to use GPS or AFLT to determine position. However, as noted GPS may not always be available and AFLT tends to be costly. Another approach to position determination involves the use of Wi-Fi, which is much cheaper than AFLT. Each Wi-Fi access point has a unique Media Access Control (MAC) address associated with it, and readable by mobile devices in the vicinity of the Wi-Fi access point. Thus, if the position of a particular Wi-Fi access point and its MAC address are known, a location service can look-up the position of a mobile device using the MAC of the Wi-Fi access point. With this later approach to position determination through Wi-Fi, the issue becomes obtaining position information and MAC addresses with regard to the many Wi-Fi access points, both public and private, deployed across various geographic regions.
Currently, correlation of MAC addresses and position information for Wi-Fi access points is done in two ways. Both rely on collecting the precise position of a Wi-Fi access point using GPS. In one approach, the company that builds a database of Wi-Fi access points (e.g., Google) puts scanning devices on vehicles and drives the vehicles on roads while tracking GPS position. As such a device scans for MAC addresses, it records the address and signal strength of each detected access point together with the corresponding position data in a database. In the other approach, software probes are bundled with location enabled applications installed on mobile devices (e.g., Google Maps) to cause the mobile devices to scan for MAC addresses and send addresses back to a server with the GPS coordinates of the mobile device. Since all wireless handsets support GPS due to government e911 mandate, all new handsets have GPS receivers.
The two methods described above require GPS access to associate a MAC address with a position (e.g., latitude and longitude coordinates). As noted earlier, there are areas where GPS may not be available to provide the position data to associate with a MAC address of a detected Wi-Fi access point.